Veritas Storage Foundation Intelligent Storage Provisioning 5.0.1 Administrators Guide, HP-UX 11i v3, First Edition, November 2009

To create an empty volume for use by a full-sized instant or linked break-off
snapshot
1
Use the vxprint command on the original volume to find the required size
for the snapshot volume.
# LEN=‘vxprint [-g diskgroup] -F%len volume‘
The command shown in this and subsequent steps assumes that you are using
a Bourne-type shell such as sh, ksh or bash. You may need to modify the
command for other shells such as csh or tcsh.
2
Use the following vxassist command to create a volume, snapvol, of the
required size and redundancy:
# vxassist [-g diskgroup] [-P storage_pool] make snapvol \
$LEN [storage_specification ...] [attribute ...] \
type=snapshot [regionsize=size] init=active
The attribute regionsize specifies the minimum size of each chunk (or region)
of a volume whose contents are tracked for changes. The region size must be
a power of 2, and be greater than or equal to 16KB. A smaller value requires
more disk space for the change maps, but the finer granularity provides faster
resynchronization. The default region size is 64k (64KB).
If the region size of a space-optimized snapshot differs from the region size
of the cache, this can degrade the system’s performance compared to the case
where the region sizes are the same.
The init=active attribute is specified to make the volume available
immediately.
The following example creates a 10 GB mirrored volume, ttsnpvol, in the
clone storage pool, ttclpool:
# vxassist -g ttdg -P ttclpool make ttsnpvol 10g \
capability=’DataMirroring(nmirs=2)’ type=snapshot \
init=active
Creating a shared cache volume and preparing
space-optimized snapshots
If you intend to create space-optimized instant snapshots that share a cache
volume, the region size that you specify for the volume must be greater than or
equal to any region size that you specify for the cache volume. Creation of
101Administering instant snapshots
Creating a shared cache volume and preparing space-optimized snapshots